97L in Western Caribbean Still a Threat to Develop

By: Dr. Jeff Masters , 1:58 PM GMT on October 02, 2013

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A tropical disturbance (Invest 97L) over the Western Caribbean is moving to the northwest at 10 mph and is generating heavy rains over the Cayman Islands and Western Cuba. Grand Cayman Island had picked up 2.32" (59 mm) of rain as of 9:30 am EDT on Wednesday. Satellite loops show that 97L has a modest area of heavy thunderstorms that have increased substantially in areal coverage and in intensity since Tuesday, but there is little rotation apparent. Cayman Islands radar also does not show any rotation to the echoes, but there are several prominent low-level bands of heavy rain. The storm has low wind shear of 5 - 10 knots to work with, as well as an upper-air anticyclone aloft that is providing good ventilation above it. Dry air is over the Yucatan Peninsula and Gulf of Mexico, as seen on water vapor satellite loops, and this dry air is slowing development. Ocean temperatures are a very warm 29°C (84°F). An Air Force hurricane hunter flight is scheduled for Wednesday afternoon.


Figure 1. Wind forecast for 2 pm EDT Saturday October 5, 2013, from runs of the GFS model done six hours apart. The more recent run, initialized at 06Z (2 am EDT) on Wednesday, October 2 (left panel) predicts that 97L will have top winds below 35 knots (40 mph, light orange colors). This run showed the center of 97L making landfall in the Florida Panhandle about 120 miles east of Alabama late Saturday afternoon.The run initialized six hours earlier, at 00Z (right panel), showed a stronger storm, with top winds of 40 - 45 knots (46 - 52 mph.) This run showed the center of 97L making landfall near the Alabama/Florida border Saturday night. The images were generated using our wundermap with the model layer turned on.

Forecast for 97L: development into at least a tropical depression likely
Wind shear is expected to remain low on Wednesday, then steadily increase to the moderate range on Thursday, then to the high range on Friday, according to the latest SHIPS model forecast. On Wednesday night, 97L will cross the northeastern tip of Mexico's Yucatan Peninsula, bringing 3 - 6" of rain to the peninsula and to Western Cuba. Passage over the Yucatan will act to disrupt the storm. The atmosphere will grow drier as 97L moves northwards over the Gulf of Mexico on Thursday and Friday, and the drier air combined with increasing wind shear will retard development, making rapid intensification unlikely. A trough of low pressure and an associated cold front will be moving through Louisiana on Saturday, and the associated upper-level westerly winds will be able to turn 97L more to the northeast as it approaches the coast on Friday. The GFS model develops 97L into a tropical storm, and predicts landfall will occur along the Florida Panhandle. The European model, which does not develop 97L into a tropical storm, is farther west, taking the storm over Eastern Louisiana. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave 97L 2-day odds of development of 40%, and 5-day odds of 50%. I give a 30% chance 97L will be Tropical Storm Karen with top winds of 40 - 60 mph at landfall between Louisiana and the Florida Panhandle on Saturday, a 5% chance it will be stronger, and a 65% chance it will be a tropical depression or mere tropical disturbance. Heavy rains of 3 - 6" can be expected falling the coast from Louisiana to the Florida Panhandle on Saturday, even if 97L does not develop into a tropical depression.


Figure 2. MODIS satellite image of 97L, taken at 12:30 pm EDT on October 2, 2013. Image credit: NASA.

Tropical Storm Jerry in the Central Atlantic no threat
Tropical Storm Jerry continues to slowly wander over the Central Atlantic, far from land. Jerry is not a threat to any land areas.

Jeff Masters

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Quoting 1250. Drakoen:
Where is Scott? I'm sure he'd love to see these obs. lol


No kidding. He took a lot of guff this morning/ afternoon.
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1265. LargoFl
18z GFS starting to come in..............
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Quoting 1244. Tribucanes:
So is it safe to say we're looking at 45mph Karin now?


Depends. You can have TS force winds in thunderstorm complexes but the key question is do we have a closed low ??
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Should have Tropical Storm Karen in the southern GOM tomorrow outflow is looking great and SST's are very warm. The models have been shifting to the east so landfall very likely from Florida panhandle to west coast of Florida. Heavy rain threat from this system regardless of development.
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1262. GatorWX
Nasty!!

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Quoting 1183. TropicalAnalystwx13:
The NAM has went absolutely friggin' insane.



I would ask if you could move that to Pennsylvania... but nevermind. My state is no way near ready for that amount of snow this early... I am sure South Dakota's transportation Department is ready tho
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Time: 21:25:30Z
Coordinates: 20.5833N 85.1833W
Acft. Static Air Press: 977.1 mb (~ 28.85 inHg)
Acft. Geopotential Hgt: 265 meters (~ 869 feet)
Extrap. Sfc. Press: 1007.6 mb (~ 29.75 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 140° at 37 knots (From the SE at ~ 42.5 mph)
Air Temp: 21.4°C* (~ 70.5°F*)
Dew Pt: -*
Peak (10s) Flt. Lvl. Wind: 38 knots (~ 43.7 mph)
SFMR Peak (10s) Sfc. Wind: 38 knots (~ 43.7 mph)
SFMR Rain Rate: 6 mm/hr (~ 0.24 in/hr)

Member Since: June 20, 2012 Posts: 0 Comments: 2169
1259. VR46L
Quoting 1173. sar2401:

Ah, should have remembered the 999 vs 998 discussion for last night. I apologize. However, I have zero confidence that this will ever be a 990 mb hurricane. I will be happy if we can four or five inches of rain though.


Sorry I should have blown it up ... Its 990



On Levi's site
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Time: 21:23:00Z
Coordinates: 20.6667N 85.1333W
Acft. Static Air Press: 976.8 mb (~ 28.84 inHg)
Acft. Geopotential Hgt: 269 meters (~ 883 feet)
Extrap. Sfc. Press: 1007.8 mb (~ 29.76 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 122° at 40 knots (From the ESE at ~ 46.0 mph)
Air Temp: 20.9°C (~ 69.6°F)
Dew Pt: 20.9°C (~ 69.6°F)
Peak (10s) Flt. Lvl. Wind: 41 knots (~ 47.1 mph)
SFMR Peak (10s) Sfc. Wind: 57 knots (~ 65.5 mph)
SFMR Rain Rate: 35 mm/hr (~ 1.38 in/hr)

Looks to me like this is Karen.
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SHOWERS AND THUNDERSTORMS ASSOCIATED WITH AN AREA OF LOW PRESSURE
OVER THE NORTHWESTERN CARIBBEAN SEA HAVE BECOME BETTER ORGANIZED
OVER THE PAST SEVERAL HOURS...AND THE SYSTEM HAS THE POTENTIAL TO
DEVELOP INTO A TROPICAL DEPRESSION AT ANY TIME DURING THE NEXT DAY
OR TWO. THE LOW IS EXPECTED TO MOVE NORTHWESTWARD TO NORTH-
NORTHWESTWARD NEAR OR OVER THE NORTHEASTERN PORTION OF THE YUCATAN
PENINSULA LATER TODAY...AND INTO THE SOUTHERN GULF OF MEXICO
TONIGHT OR THURSDAY. THIS SYSTEM HAS A HIGH CHANCE...70 PERCENT...
OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. AFTER
THAT...STRONG UPPER-LEVEL WINDS ARE LIKELY TO LIMIT DEVELOPMENT AS
THE SYSTEM APPROACHES THE NORTHERN GULF OF MEXICO BY THE WEEKEND.
THIS SYSTEM HAS A HIGH CHANCE...70 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 5 DAYS. LOCALLY HEAVY RAINS COULD AFFECT
THE CAYMAN ISLANDS...PORTIONS OF CUBA...AND PORTIONS OF THE YUCATAN
PENINSULA DURING THE NEXT DAY OR TWO.



Likely to limit development. That means it can still strengthen but at a slower rate. Dry air seems to be no real problem as it has made a moisture barrier keeping dry air OUT. Shear might be a small problem but it might still be able to strengthen very slooowwwwllllyyyyy.
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Quoting 1229. LAbonbon:


RGV - 2 ft? That graphic seems to be showing upwards of 4 ft in parts of S. Dakota

I mistyped sorry..meant to say 4 ft. :P
Member Since: May 30, 2013 Posts: 0 Comments: 567
Scott was close enough with his call of a 40kt tropical storm earlier.

Doubt the rest of his predictions come true though.
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1254. Patrap
Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 2nd day of the month at 21:28Z
Date: October 2, 2013
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 301)
Mission Purpose: Investigate sixth suspect area (flight in the North Atlantic basin)

Mission Number: 1

Observation Number: 38



21:28:30Z 20.483N 85.300W 977.0 mb
(~ 28.85 inHg) 262 meters
(~ 860 feet) 1006.9 mb
(~ 29.73 inHg) - From 145° at 25 knots
(From the SE at ~ 28.7 mph) 22.2°C*
(~ 72.0°F*) -* 26 knots
(~ 29.9 mph) 29 knots
(~ 33.3 mph) 6 mm/hr
(~ 0.24 in/hr) 27.9 knots (~ 32.1 mph)
111.5%
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor

HDOB Observations

Independent Calculations from Tropical Atlantic

At 21:19:00Z (first observation), the observation was 100 miles (161 km) to the ESE (109°) from Cancún, Quintana Roo, México.

At 21:28:30Z (last observation), the observation was 109 miles (176 km) to the ESE (115°) from Cancún, Quintana Roo, México.
Member Since: July 3, 2005 Posts: 428 Comments: 129841
Jeff-CapitalWeatherGang
2:45 PM EDT
GFS 5-6 day tracks the post-tropical remnant and a heavy bullseye of precip right
over DC-Baltimore. I'm not certainly hedging any bets on a 5-6 day forecast, but
the combo of tropical energy & moisture, orography and baroclinic interaction could
definitely spell heavy rain for someone in the Mid Atlantic. We'll have to keep a
shrewd eye on the post-tropical evolution of this one...especially since there's the
hint of an upper trough interaction over the southeast U.S.

Looks like the rainy pattern that usually set's up over D.C here in October will get off on a good start :).
Member Since: August 14, 2010 Posts: 10 Comments: 17810
1252. sar2401
Quoting hydrus:
A more thorough investigation of this system this time out may save on gas and time later. After all, we are a government that currently is closed until further notice...

Not true, and you know it. The funding for the hurricane hunters has not been affected. "non-essential" personnel have been furloughed. To put this in perspective, about 2 million civilian employees, not including the Armed Forces or the Post Office. There at least 300,000 consultants that have contracts with the Federal Government. There no numbers on how many of these contractors considered "essential". Assuming about half of them are still working, about 37% of Federal employees/contractors are not at work today. That may be a good starting point to consider how many Federal employees we really need. When I go to the NHC site and read:

Due to the Federal Government shutdown, NOAA.gov and most associated web sites are unavailable. However, because the information this site provides is necessary to protect life and property, it will be updated and maintained during the Federal Government shutdown.

It shows either none of our Federal government employees are able to program a web site that will run for more than one day unattended or this is clearly a good propaganda move to make things seem really bad at NOAA because all the "non-essential" employees aren't there. You decide.
Member Since: October 2, 2004 Posts: 0 Comments: 17358
Quoting 1243. will40:
55.6 knots (~ 64.0 mph)
Tropical Storm

Rain rate is over 1", contaminated data.
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1250. Drakoen
Where is Scott? I'm sure he'd love to see these obs. lol
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Quoting 1243. will40:
55.6 knots (~ 64.0 mph)
Tropical Storm


Flagged.
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43 flt; 57 sfmr...no flags on either. (have a 59 but with a flag on it)
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1247. GatorWX
Nice loop:

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Quoting 1235. MississippiWx:
Heading back for a new pass.



The recon was just to the north-west of the blob..
Member Since: June 20, 2012 Posts: 0 Comments: 2169
1245. GetReal
New just released steering layer from CIMSS:



The highway into the GOM and the northern GOM is WIDE OPEN.
Member Since: July 4, 2005 Posts: 204 Comments: 8898
So is it safe to say we're looking at 45mph Karin now?
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1243. will40
55.6 knots (~ 64.0 mph)
Tropical Storm
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Quoting 1235. MississippiWx:
Heading back for a new pass.



They are really getting their runs in. Maybe with this government shutdown nonsense they are trying to get as much as they can in each trip
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Quoting 1231. kmanislander:
I hope they have enough fuel to stick around for another hour or two. This is starting to look interesting


They can stay airborne for around 11/12 hours.
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Quoting 1231. kmanislander:
I hope they have enough fuel to stick around for another hour or two. This is starting to look interesting



ULAC overhead and Rocket Fuel SST's to boot. Things could happen very quickly.
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1239. LargoFl
Quoting 1221. Broward:
moisture from 97L? Falls Mall under water in south Miami

AT 430 PM EDT NATIONAL WEATHER SERVICE DOPPLER RADAR ESTIMATES
RAINFALL TOTALS ARE NOW IN THE 5 TO 6 INCH RANGE JUST SOUTHWEST OF
KENDALL AND UP TO 1 TO 3 INCHES FROM TAMIAMI FAIRGROUNDS TO WEST
KENDALL. AN ADDITIONAL 1 TO 2 INCHES IN THE HEAVIER ACTIVITY
TRACKING OVER THE AREA WILL REMAIN POSSIBLE WITHIN THE UPCOMING 1 TO
2 HOURS. ALTHOUGH NO ROAD CLOSURES HAVE BEEN REPORTED AT THIS
POINT...SOME OF THE TYPICALLY VULNERABLE ROADS MAY BE IMPASSABLE.
you folks sure had alot of rain down there today.
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It only takes one..
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1237. Drakoen
Quoting 1232. Tribucanes:


Would seem a recipe for a strong TS in 24hrs. Too early for thoughts and prognostication from you Drakoen based on what your observing?


The conditions in its current position are conducive to further development.
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1236. Torito
45KT winds detected. thats like... 49mph winds.

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Heading back for a new pass.

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1234. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 178 Comments: 56059
1233. will40
34.0 knots (~ 39.1 mph)
Tropical Storm


just need to find her closed
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Quoting 1218. Drakoen:


In the right front quadrant. Seems about right. This could miss the Yucatan Peninsula and go through the Channel.


Would seem a recipe for a strong TS in 24hrs. Too early for thoughts and prognostication from you Drakoen based on what your observing?
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I hope they have enough fuel to stick around for another hour or two. This is starting to look interesting

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Quoting 1217. GatorWX:


Certainly has some decent support from the surface.


"Looks" like a duck to me. Recon will give the for sure though. If there is something under there that is.
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Quoting 1207. RGVtropicalWx13:
Remember folks the nam is great for with winter not tropics. Although snow is likely there. 2 ft is insane and unlikely to occur. Might've had a major feed back this run.


RGV - 2 ft? That graphic seems to be showing upwards of 4 ft in parts of S. Dakota
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Quoting 1212. GatorWX:
Approaching dmin soon. Relentless today huh??

I keep telling you all what-will-be-Karin is on a mission..Revenge sort of Speak..
Member Since: August 14, 2010 Posts: 10 Comments: 17810
Thanks Rick!

Mike

Quoting 1209. RickWPB:


Mfcmom, A good link for models and just about everything else you might want to look at is here:

Mike's Weather Page
Link
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1226. Drakoen
Quoting 1215. JrWeathermanFL:
Where that eye-like feature randomly came up, and now there's a bust of convection there??
ehhh


LOL.
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Time: 21:18:00Z
Coordinates: 20.6833N 85.4167W
Acft. Static Air Press: 976.8 mb (~ 28.84 inHg)
Acft. Geopotential Hgt: 269 meters (~ 883 feet)
Extrap. Sfc. Press: 1007.3 mb (~ 29.75 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 133° at 32 knots (From the SE at ~ 36.8 mph)
Air Temp: 22.3°C (~ 72.1°F)
Dew Pt: 22.2°C (~ 72.0°F)
Peak (10s) Flt. Lvl. Wind: 34 knots (~ 39.1 mph)
SFMR Peak (10s) Sfc. Wind: 35 knots (~ 40.2 mph)
SFMR Rain Rate: 7 mm/hr (~ 0.28 in/hr)
Member Since: June 20, 2012 Posts: 0 Comments: 2169
1224. GatorWX
Quoting 1218. Drakoen:


In the right front quadrant. Seems about right. This could miss the Yucatan Peninsula and go through the Channel.


Kinda been thinking that...



...or barely scrape it.
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1223. Torito
Quoting 1218. Drakoen:


In the right front quadrant. Seems about right. This could miss the Yucatan Peninsula and go through the Channel.


yea, and that would be beneficial to the storm. hitting land really weakens these kind of systems.
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Quoting 1215. JrWeathermanFL:
Where that eye-like feature randomly came up, and now there's a bust of convection there??
ehhh

:O
Hidden message much?
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1221. Broward
moisture from 97L? Falls Mall under water in south Miami

AT 430 PM EDT NATIONAL WEATHER SERVICE DOPPLER RADAR ESTIMATES
RAINFALL TOTALS ARE NOW IN THE 5 TO 6 INCH RANGE JUST SOUTHWEST OF
KENDALL AND UP TO 1 TO 3 INCHES FROM TAMIAMI FAIRGROUNDS TO WEST
KENDALL. AN ADDITIONAL 1 TO 2 INCHES IN THE HEAVIER ACTIVITY
TRACKING OVER THE AREA WILL REMAIN POSSIBLE WITHIN THE UPCOMING 1 TO
2 HOURS. ALTHOUGH NO ROAD CLOSURES HAVE BEEN REPORTED AT THIS
POINT...SOME OF THE TYPICALLY VULNERABLE ROADS MAY BE IMPASSABLE.
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Quoting 1183. TropicalAnalystwx13:
The NAM has went absolutely friggin' insane.


And this is why you don't drink and forecast folks. NAM your drunk.
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Quoting 1214. Torito:
TS FORCE WINDS!



Oh boy.

TS Karen here we come.
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1218. Drakoen
Quoting 1214. Torito:
TS FORCE WINDS!




In the right front quadrant. Seems about right. This could miss the Yucatan Peninsula and go through the Channel.
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1217. GatorWX
Quoting 1211. ProgressivePulse:
I think the COC has developed back at 20N 85W personally.


Certainly has some decent support from the surface.
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There doesn't appear to be any shear present in WV loops to cause the CDO "looking" feature to be off the center.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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